In a vehicular traffic system, a probe source (e.g., a probe vehicle equipped with a global positioning system or GPS and/or a commuter equipped with a mobile phone) may transmit periodic satellite-based probe reports indicative of traffic conditions in the vicinity of the probe source. These probe reports may then be processed by a traffic system to model or estimate road conditions (e.g., traffic flow, congestion, travel speed, travel time, etc.), which may be reported back to the system's clients and/or otherwise stored and/or processed.